[Features] Added CoroutineAccessors.

Author: nate-chandler

include/swift/AST/PrintOptions.h

@@ -390,6 +390,9 @@ struct PrintOptions {
   /// Suppress ~Escapable types and lifetime dependence annotations
   bool SuppressNonEscapableTypes = false;
 
+  /// Suppress modify/read accessors.
+  bool SuppressCoroutineAccessors = false;
+
   /// List of attribute kinds that should not be printed.
   std::vector<AnyAttrKind> ExcludeAttrList = {
       DeclAttrKind::Transparent, DeclAttrKind::Effects,

include/swift/AST/StorageImpl.h

@@ -49,6 +49,22 @@ enum class AccessorKind {
 #undef LAST_ACCESSOR
 };
 
+inline bool requiresFeatureCoroutineAccessors(AccessorKind kind) {
+  switch (kind) {
+  case AccessorKind::Get:
+  case AccessorKind::DistributedGet:
+  case AccessorKind::Set:
+  case AccessorKind::Read:
+  case AccessorKind::Modify:
+  case AccessorKind::WillSet:
+  case AccessorKind::DidSet:
+  case AccessorKind::Address:
+  case AccessorKind::MutableAddress:
+  case AccessorKind::Init:
+    return false;
+  }
+}
+
 inline bool isYieldingAccessor(AccessorKind kind) {
   switch (kind) {
   case AccessorKind::Read:

include/swift/Basic/Features.def

@@ -417,6 +417,9 @@ EXPERIMENTAL_FEATURE(ValueGenerics, true)
 // When a parameter has unspecified isolation, infer it as main actor isolated.
 EXPERIMENTAL_FEATURE(UnspecifiedMeansMainActorIsolated, false)
 
+/// modify/read single-yield coroutines
+SUPPRESSIBLE_EXPERIMENTAL_FEATURE(CoroutineAccessors, true)
+
 #undef EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE
 #undef EXPERIMENTAL_FEATURE
 #undef UPCOMING_FEATURE

lib/AST/ASTPrinter.cpp

@@ -3112,6 +3112,13 @@ suppressingFeatureNonescapableTypes(PrintOptions &options,
   options.ExcludeAttrList.resize(originalExcludeAttrCount);
 }
 
+static void
+suppressingFeatureCoroutineAccessors(PrintOptions &options,
+                                     llvm::function_ref<void()> action) {
+  llvm::SaveAndRestore<bool> scope(options.SuppressCoroutineAccessors, true);
+  action();
+}
+
 /// Suppress the printing of a particular feature.
 static void suppressingFeature(PrintOptions &options, Feature feature,
                                llvm::function_ref<void()> action) {
@@ -3990,6 +3997,10 @@ bool PrintAST::printASTNodes(const ArrayRef<ASTNode> &Elements,
 }
 
 void PrintAST::visitAccessorDecl(AccessorDecl *decl) {
+  if (Options.SuppressCoroutineAccessors &&
+      requiresFeatureCoroutineAccessors(decl->getAccessorKind())) {
+    return;
+  }
   printDocumentationComment(decl);
   printAttributes(decl);
   // Explicitly print 'mutating' and 'nonmutating' if needed.

lib/AST/FeatureSet.cpp

@@ -319,6 +319,14 @@ static bool usesFeatureValueGenerics(Decl *decl) {
   return false;
 }
 
+static bool usesFeatureCoroutineAccessors(Decl *decl) {
+  auto *accessor = dyn_cast<AccessorDecl>(decl);
+  if (!accessor) {
+    return false;
+  }
+  return requiresFeatureCoroutineAccessors(accessor->getAccessorKind());
+}
+
 // ----------------------------------------------------------------------------
 // MARK: - FeatureSet
 // ----------------------------------------------------------------------------

lib/ASTGen/Sources/ASTGen/SourceFile.swift

@@ -74,6 +74,7 @@ extension Parser.ExperimentalFeatures {
     mapFeature(.DoExpressions, to: .doExpressions)
     mapFeature(.NonescapableTypes, to: .nonescapableTypes)
     mapFeature(.TrailingComma, to: .trailingComma)
+    mapFeature(.CoroutineAccessors, to: .coroutineAccessors)
   }
 }